1. Field of the Invention:
This invention relates to railway cars, which employ a connection between two rigid elements. The connection facilitates angular deflection or rotation, of one of the elements relative to the other element, in all directions while still limiting the elastic eccentricity between the two rigid elements.
2. Description of the Prior Art:
The prior art discloses various devices for spherical, or rotational, articulation, or movement, around a point. One device is, simply, a metal swivel having a spherical head and a foot, which also may be conical, fastened on a support by means of a bolt. The socket which holds the swivel can be made from two pieces of metal; one piece being hemispheric and the other piece being ring-shaped around the base of the swivel. A spring, or conical washer, may provide an elastic prestress. This device is that which has been disclosed by Lemfoerder Metal and also disclosed in German Patent No. 3,536,283.
A one-piece socket, made of plastic material, performs the same function, described above, as disclosed in U.S. Pat. No. 3,249,375, which is assigned to TRW, German Patent No. 2,031,374, which is assigned to TRW Inc. and French Patent No. 2,170,608, which is assigned to TOKAI TRW. This socket provides a certain filtering of vibrations by a polyethylene or polypropylene material and makes possible an omnidirectional prestress. Great Britain Patent No. 1,517,901, which is assigned to Ehrenreich, also describes a process for the construction of this type of swivel joint by direct stamping of the casing around the plastic socket.
In the prior art, the rubber-metal joint, in which rubber is adherized to the metal by vulcanization, has been used to improve the spherical swivel joint by eliminating any contact of metal on metal. The transmission of vibrations and the need for lubrication may, thereby, be reduced. A 1972 brochure, labeled 121/1 from Kleber, which discloses a spherical swivel joint licensed by Metalastik under the name "Spherilastik", describes the advantages of this type of design. An exterior ring, which is fabricated in three sectors in an opening, produces a radial prestress within a rubber, or elastomer material, by bringing together the spherical surfaces of the ring and provides a connection between the rubber, or elastomer, material and the ring.
The prestress provides an improved resistance to alternating fatigue and, also, provides a rigidity of the elastic connection between the two solid, or rigid elements which is limited only by deterioration of the rubber or elastomer, by metal-on-metal contact, or by friction, between the opening and a fastening shaft, or axis. This configuration achieves a maximum travel which varies with the angular position. Other techniques to apply prestress to vulcanized rubber-metal connections can be used on the swivel joints to bring the rigid elements axially closer together. European Patent No. 0,148,073 discloses a gasket for elevated-pressure tubes and hoses which employs an elastomer swivel joint which is prestressed, or compressed, by an axial geometric deformation.
With all of the above-recited devices, the relative movement of the rigid elements, which face one another and are separated by a spherical swivel made of banded elastomer, causes elastic deformation at an essentially, constant rigidity over a significant axial length of movement. Such movement may be as much as one-quarter of the thickness of the elastomer, before a deterioration, or breakdown, of the elastomer occurs. Such breakdown may occur due to detachment between the elastomer and the metal or due to bursting of the elastomer.
Situations exist where such elasticity and the corresponding displacement are disadvantageous. If a stop must be provided for either sudden or gradual motion change, and if the stop must be outside the elasticity swivel joint, then the stop takes up a considerable amount of space, otherwise the rigid surfaces which can come in contact with one another after a slight travel would not remain facing one another, irrespective of the orientation of the swivel joint. This may be possible only for spherical surfaces which are concentric with the surfaces of the elastomer swivel, which must be carefully adjusted on their supports, since the fabrication tolerances accumulate.
The prior art does not disclose an elastic swivel joint, capable of limiting elastic eccentricity and filtering vibrations which employs a vulcanized rubber/metal connection and which takes up little space.